Nanorings

Pyykko, P. and Zaleski-Ejgierd, P. (2008) From nanostrips to nanorings the elastic properties of gold-glued polyauronaphthyridines and polyacenes. Physical Chemistry Chemical Physics, 10, 114-120. 

Suematsu, N. J., Ogawa, Y., Yamamoto, Y. and Yamaguchi, T. (2007) Dewetting self-assembly of nanoparticles into hexagonal array of nanorings./. Colloid. Interface Sci., 310, 684-652. 

Jiang L-P, Xu S, Zhu JM, Zhang JR, Zhu JJ, Chen HY (2004) Ultrasonic-assisted synthesis of monodisperse single-crystalline silver nanoplates and gold nanorings. Inorganic Chem 43 5877-5883... 

B., Zhang, M. and Yu, S.H. (2008) High yield synthesis of bracelet-like hydrophilic Ni-Co magnetic alloy flux-closure nanorings. Journal of the American Chemical Society, 130 (35), 11606-11607. 

Numerous nanostructures such as nanorods, nanotubes, or nanorings have been obtained by this approach. In particular, the use of organoge-lators as directors to control the morphologies of the aggregates has been explored recently. Cholesterol- and phospholipid-thethered trans-styl-benes are able to gelate different organic solvents in which the steroid and the lipid units serve as templates to form one-dimensional stacks. 

Hoffmann, M., Wilson, C. J., Odell, B., Anderson, H. L., Template-directed synthesis of a pi-conjugated porphyrin nanoring. 

Crystalline nanorings, literally closed circular nanoparticles with a hollow centre, were first prepared from zinc oxide in 2004 by a spontaneous self-coiling process from polar nanobelts.44 Semiconductor nanorings and indeed interestingly shaped nanoobjects in general, promise much in the way of applications as tools to probe fundamental physical phenomena and as nanoscale sensors, transducers, and resonators. 

Figure 1. Typical nanostructure geometries (a) chain of fine particles, (b) striped nanowire, (c) cylindrical nanowire, (d) nanodots, (e) nanojunction, (f) nanotube, (g) antidots, (h) vicinal surface step, (j) nanoring, and (k) patterned thin film. Note that the figures can consist of multilayered and granular nanocomposites.

Figure 1. CNTs and other nano-sized carbon particles (a) scrolling a graphene sheet (b) closed and opened single-walled CNT (c) double-walled CNT (d) CNT sites doped with boron and nitrogen (e) nanopipettes (f) nanocones and (g) nanorings.

The synthesis of other nano-sized carbon structures (nanocones,9 nanopipettes10 and nanorings,11 presented in Figure le-g) has been recently reported. These structures have promising mechanical, electronic and surface properties, and are of interest for applications in nano-scale devices. 

FIGURE 21 TEM image of Gd20j nanorings. Unlabeled scale bars correspond to 2.5 nm. Reprinted with permission from Paek et al. (2007). Copyright 2007 American Chemical Society. 

Paek et al. (2007)reported the synthesis of colloidal nanorings and nanoplates of several rare earth metal oxides from thermal dehydration of hydrolyzed metal precursor-surfactant aggregates (Figure 21). The Gd (acac)3 precursor was hydrolyzed at a low temperature of 90 °C and latter, the hydrolyzed precursor-surfactant aggregates were heated to 320 °C for thermal decomposition. Colloidal cubic R2O3 nanorings and nanoplates were obtained. 

How would you synthesize free-standing nanorings using both the top-down and bottom-up approaches ... 

Figure 10.22 (a) Seamless single-crystal nanorings ofZnO (b) Bright-field and (c) dark-field TEM images of a nanoring. 

Galvanic replacement reactions with small silver nanoparticies have been studied in detail by Lu et al. [132], They found that a complete gold shell did not form on the surface of each individual silver nanoparticle template. Instead, the replacement reaction resulted in the formation of alloy nanorings and nanocages from multiply-twinned silver nanoparticies of decahedral or icosahedral shape. 

Sun, Y. and Xia, Y. (2003). Triangular nanoplates of silver Synthesis, characterization, and use as sacrificial templates for generating triangular nanorings of gold. Adv. Mater. 15 695-699. 

Synthesis of one dimensional, two dimensional and three dimensional nanostructured metal oxides have attracted a great deal of interest for the past many years. Because of their size dependent catalytic and optoelectronic properties, they can be broadly tuned through size variation. Recently, extensive efforts have been made to synthesize one dimensional metal oxides nanostructures such as nanowires, nanobelts, nanotubes, nanorods, nanorings etc [Fig.2], Various methods have been used in literature for development of nanostructured metal oxides of varying shape and sizes are as follows. 

These include nanoshells [359] composed of a dielectric core coated by a thin layer of metal nanodisks and nanorings [360], These unique nanoparticles exhibit plasmon resonance frequencies in the near-infrared at dimensions significantly smaller than 100 nm. By variation of the aspect ratio of these particles, it is possible to tune the plasmon resonance frequency as well as the cross sections for scattering and absorption, respectively. 

Figure 4.13 Fullerene molecule in a complex with two carbon nanorings. This is a first step to a rational synthesis of multilayered carbon objects.

The calculations are preceded by a detailed review of experimental and theoretical work on many-body luminescence from various infinite systems. We also review the current status of the experimental and theoretical research on quantum nanorings. 

Since many-body optical transitions in zero-dimensional objects was demonstrated experimentally, it is important to assess this phenomenon from the perspective of the well established field of many-body luminescence. This is accomplished in the present chapter. Below we review the many-body luminescence in various systems studied to date experimentally and theoretically. We then demonstrate that many-body luminescence from highly excited zero-dimensional objects has unique features due to large number of discrete lines. This discreteness unravels the many-body correlations that are otherwise masked in the continuous spectrum of luminescence from infinite systems. We describe in detail the emergence of such correlations for a particular nanostructure geometry - semiconductor nanorings - using the Luttinger liquid approach for quasi-one-dimensional finite-size systems. 

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